Artist Yoko Ono was admitted to hospital after having "serious flu" and not because of a stroke, her agent confirmed. The 83-year-old, who was married to Beatles legend John Lennon until he was shot dead in 1980, went to hospital on Friday night.

Elliot Mintz denied media reports that she suffered a stroke and said she will be discharged on Saturday, (27 February). Her son, Sean, took to Twitter to thank everyone for their concern.

He told ABC News: "To the best of my knowledge, she had symptoms along the lines of a serious flu, and her doctor thought it was best that she would get a check-up at the hospital. There is no stroke and there are no lifet-hreatening circumstances as has been described to me. It's just an advanced case of the flu."

Yoko Ono, a prolific artist and campaigner, met John Lennon while she exhibited her artwork at a gallery in 1966. Lennon reportedly once described his wife as "the world's most famous unknown artist: everyone knows her name but no one knows what she actually does".

John Lennon and Yoko Ono
Lennon\'s and Ono\'s iconic Rolling Stone cover Rolling Stone

Concerning his death, she told the Telegraph, four years ago: "John's death was the worst of everything. I had to work hard to un-curse myself."

A known feminist who is never scared to speak her mind, she posted a letter on her website last year warning her critics to leave her – and singing voice – alone.

She wrote: "Let me be free. Let me be me! Don't make me old, with your thinking and words about how I should be. You don't have to come to my shows. I am giving tremendous energy with my voice, because that is me. Get my energy or shut up.

"I am afraid of just one thing. That those ageism criticism will finally influence me, I would succumb to it and get old. So I am covering my ears not to listen to you guys! Because dancing in the middle of an ageism society is a lonely trip. Don't stone me! Let me be! Love me plenty for what I am!"

John Lennon was gunned down by Mark Chapman on December 8, 1980, outside the Dakota apartment building in New York City. Yoko Ono still lives in the same building.